Spark arrester



Oct. 19 1.926.

1,603,279 P GRAY SPARK AR'RESTER Filed Dec. 1, 1922 fran/r Gray. yi

Patented Oct. 19, 1926.

UNITED STATESl .1,603,279 PATENT OFFICE.,

FRANK GRAY, OF NEW YORK, N.' Y., ASSIGNOB TO WESTERN ELECTRIC COMIfANY, IN- CORPORATED, OF NEW YORK, N. Y., A. CORPORATION OF NEW YORK.

SPARK ABKESTEB.

4Application: illed December 1, 1922. Serial Np. 604,152.

` This invention relates to means for preventing sparking at relay or like contacts,

and its object is an improved spark arrester which is simple in construction, ositive in operation and in which the cost'o /manufacture is reduced to a minimum.

In its preferred form the invention., conv sists essentially of a short spark gap or valve formed of two. simple punchings enl'0 closed in a glass tube containin an-easily ionized gas at a low pressure. is gap is normally inoperative when connected across a pair of electrical contacts, but as soon as the contacts commence to separate, the voltage induced in the circuit quickly breaks down the gap and by-passes the current which accompanies the dissipation of the ma etic energy in the circuit.

T e size, rug edness and responsiveness of the device are a so features of the invention, as will appear from a consideration of the following description, taken in connection .with the following drawing, in which:

Fig. 1 is a front elevation showing the in-4 vention in its preferred form.

Fig.g2 is an enlar edsectional view taken on the kline 2-2 of ig. 1.

Fig. 3 is an enlar ed sectional view taken on the line 3 3 of ig. 1.

Fig. 4 is a diagrammatic view of an inductive relay circuit embodying the invention.

Referring to the drawing, the invention comprises two small parallel aluminum plates or electrodes 5 and 6, separated by a few thousandths of aninch, and sealed wlthin a glass tube-,7. While aluminum has been used with great success, electrodes of iron and tin have proved equally effective. For ordinary purposes the plates 5 and 6 are about 5% long by 1A, wide, and ma readily be contained 1n a tube about 11/ long. The simple-'mechanical structure t 'at el mits the small plate separation is shown in Figs. 1 and 2. The plates 5 and 6 consist 0f single punchings, the plate 6 being a iat strip whilethe plate 5 is formed near each end with loops or de ressions 8 and 9, and is also provided wit end tabs 10 and 11 preferably formed integral therewith. The plate 6 is wrapped at its ends with strips 12 and 13 of mica or other suitable insulating material held in place bythe tabs 10 and 11 of the late 5 which are ybent over and f. ressed own when the plates 5 and 6 are rought together. An important feature. of

this construction is that there are no short paths across the ends of the mica strips 12 and 13, these strips being extended beyond the ends of the plates 5 and 6, and also extending into the region where the plates are widely separated by the loops 8 and 9. Since the plates 5 and 6'are widely separated at wires 14 and 15 are sealed into the base of l,

the tube 7 and are attached inside the tube to tabs 16 and 17, res ectively,.formed integral with and depen ing from the ends of the platesV 5 and 6, and serve to su port and correctly center the plates within tiie tube.

The spark arrester described above forms an effective quick-acting gap which may be employed to shunt an opening relay contact, the gap breaking down at a lower voltage than the air ga at the relay contact. SparkV aps that brea down at low voltages have een employed as lightning arresters, but Such gaps will not rotect an opening con-l tact on account of t e time lag l1n their acythe gap starts to conduct. An important feature of the above described spark arrester is its rapidity of breakdown which enables it to completely protect l,a relay Contact against air sparking. This rapidity of breakdown is due to the small separation of the plates which form'the gap, to the presence in the tube of an easily ionized gas, and probably to the use of electrodes of aluminum, iron, tin or other metalswhich are usually coated with a conducting rather than an insulating oxide. The gas contained in the tube consists of argon containing about 10% of hydrogen at a pressure of 8 to 10 c. m, of mercury. A spark arrester or valve of this type will completely arrest the sparks that normally occur at an openin relay contact.

he operation of the device is shown in Fig. 4 in which the arrester is connected lll() suitable means.

which are included in a circuit 2O with a battery 21 and an inductance 22. The spark arrester is normally inoperative when the contacts 18 and 19 are closed, the battery circuit when this condition prevails being traceable from one side ot the battery 21, throughl contacts 19 and 18, and inductan-ce 22 to the other side of batteri7 21. The contact 18 is controlled by a relay 23, and when this relay is |deenergized the contacts 18 and/19 separate by gravity or any o-her As soon as the contacts 18 and 19 commence to separate, the voltage induced in the circuit 20 quickly breaks down the ga between the plates 5 and 6 of the tube@ and by-passes the current, completely taking up the spark.

Obvious changes in the materials and details of construction described above will occur to any one skilled in the art, and it is therefore to be 'understood that the invention is not limited to any specific con` struction except as defined by the appended claims.

The invention claimed is:l y

1; In an protective device, a. receptacle, a

gap in said receptacle comprising a pair of parallel electrodes, one of said electrodes being looped near its ends, strips of insulating material around the ends of the other electrode and extending within said loops and over the` ends of said electrode and tabs formed on said looped electrode and bent over said insulating strips to hold said electrodes together.

2. In a protective device, a receptacle, a gap in sald receptacle comprising a pair of parallel electrodes, one of said electrodes being looped near its ends, strips of insulating material around the ends of:- the other electrode and extending within said loops and over the ends of said electrodes, tabs formed on said looped electrode and bent over said insulating strips to hold said electrodes together and an easily ionized gas maintained in said receptacle at a low pressure.

In witness whereof, I hereunto subscribe f my name this 28th day of November A. D., 4 1922.

FRANK GRAY. 

